The roles of costs, attitudes, and previous contraceptive practices in the European fertility transition will be investigated in a study of Verviers, Belgium. Unusual research opportunities exist because of population registers which can be used for family reconstitution. Samples will be used to determine the social composition of early participants in the new pattern of family limitation. Family histories of men with known political ideologies will be studied for the effects of ideas on fertility behavior. A time series analysis of shortrun changes in birth rates in response to economic fluctuations will examine the relationship of voluntary control in the pre-transition period to the beginnings of family limitation. This information will be used to distinguish between theories of fertility decline which emphasize changes in economic costs of children and those which stress attitudes or the concept of family limitation.